方法一
处理HTMLString的方法：
NSString *htmls = [NSString stringWithFormat:@"<html>
"
"<head>
"
"<style type="text/css">
"
"body {font-size:15px;}
"
"</style>
"
"</head>
"
"<body>"
"<script type='text/javascript'>"
"window.onload = function(){
"
"var $img = document.getElementsByTagName('img');
"
"for(var p in $img){
"
" $img[p].style.width = '100%%';
"
"$img[p].style.height ='auto'
"
"}
"
"}"
"</script>%@"
"</body>"
"</html>",htmlString];
[self.webView loadHTMLString:htmlString baseURL:nil];
处理HTMLString的原理：
原理就是用一个for循环，拿到所有的图片，对每个图片都处理一次，让图片的宽为100%，就是按照屏幕宽度自适应；让图片的高atuo，自动适应。文字的字体大小，可以去改font-size:15px，这里我用的是15px。根据自己的具体需求去改吧。
方法二
[webView stringByEvaluatingJavaScriptFromString:
@"var script = document.createElement('script');"
"script.type = 'text/javascript';"
"script.text = "function ResizeImages() { "
"var myimg,oldwidth;"
"var maxwidth=300;" //缩放系数 改变参数控制图片缩放大小
"for(i=0;i <document.images.length;i++){"
"myimg = document.images[i];"
"if(myimg.width > maxwidth){"
"oldwidth = myimg.width;"
"myimg.width = maxwidth;"
"myimg.height = myimg.height * (maxwidth/oldwidth);"
"}"
"}"
"}";"
"document.getElementsByTagName('head')[0].appendChild(script);"];
[webView stringByEvaluatingJavaScriptFromString:@"ResizeImages();"];